MOS type solid-state image pickup device and driving method comprised of a photodiode, a detection portion, and a transfer transistor

1. A solid-state image pickup device including: a plurality of pixels each comprising (1) a photodiode, (2) a detection portion and (3) a transfer transistor for transferring charges accumulated in said photodiode to said detection portion, wherein, an overflow path for discharging charges overflowing from said photodiode is formed in a bulk out of a channel portion of said transfer transistor and discharges the charges in a depth direction of a substrate, said overflow path is formed of a first conductive type semiconductor region formed on the surface of a n-type semiconductor region in an area extending from the portion just below said photodiode to a semiconductor substrate, and said area is formed of the second conductive type semiconductor region having an impurity concentration lower than that of a semiconductor well region or the p-type semiconductor region.

2. The solid-state image pickup device as claimed in claim 1 , wherein said overflow path is formed in the area between said photodiode and said detection portion, and said area is formed of an n-type semiconductor region having an impurity concentration lower than that of a semiconductor well region or a p-type semiconductor region.

3. The solid-state image pickup device as claimed in claim 1 , wherein said overflow path is formed in an area extending from the portion just below said photodiode and the area between said photodiode and said detection portion to a semiconductor substrate, and said area is formed of an n-type semiconductor region having an impurity concentration lower than that of a semiconductor well region or a p-type semiconductor region.